/*
 [auto_generated]
 boost/numeric/odeint/stepper/explicit_error_generic_rk.hpp

 [begin_description]
 Implementation of the generic Runge Kutta error stepper. Base class for many RK error steppers.
 [end_description]

 Copyright 2009-2011 Karsten Ahnert
 Copyright 2009-2011 Mario Mulansky

 Distributed under the Boost Software License, Version 1.0.
 (See accompanying file LICENSE_1_0.txt or
 copy at http://www.boost.org/LICENSE_1_0.txt)
 */

#ifndef BOOST_NUMERIC_ODEINT_STEPPER_EXPLICIT_ERROR_GENERIC_RK_HPP_INCLUDED
#define BOOST_NUMERIC_ODEINT_STEPPER_EXPLICIT_ERROR_GENERIC_RK_HPP_INCLUDED

#include <boost/numeric/odeint/stepper/base/explicit_error_stepper_base.hpp>

#include <boost/numeric/odeint/algebra/default_operations.hpp>
#include <boost/numeric/odeint/algebra/range_algebra.hpp>
#include <boost/numeric/odeint/stepper/detail/generic_rk_algorithm.hpp>
#include <boost/numeric/odeint/stepper/detail/generic_rk_call_algebra.hpp>
#include <boost/numeric/odeint/stepper/detail/generic_rk_operations.hpp>

#include <boost/numeric/odeint/util/state_wrapper.hpp>
#include <boost/numeric/odeint/util/is_resizeable.hpp>
#include <boost/numeric/odeint/util/resizer.hpp>

namespace boost {
namespace numeric {
namespace odeint {

template <size_t StageCount, size_t Order, size_t StepperOrder, size_t ErrorOrder, class State,
          class Value = double, class Deriv = State, class Time = Value, class Algebra = range_algebra,
          class Operations = default_operations, class Resizer = initially_resizer>
#ifndef DOXYGEN_SKIP
class explicit_error_generic_rk
    : public explicit_error_stepper_base<
          explicit_error_generic_rk<StageCount, Order, StepperOrder, ErrorOrder, State, Value, Deriv,
                                    Time, Algebra, Operations, Resizer>,
          Order, StepperOrder, ErrorOrder, State, Value, Deriv, Time, Algebra, Operations, Resizer>
#else
class explicit_error_generic_rk : public explicit_error_stepper_base
#endif
{

public:
#ifndef DOXYGEN_SKIP
  typedef explicit_error_stepper_base<
      explicit_error_generic_rk<StageCount, Order, StepperOrder, ErrorOrder, State, Value, Deriv, Time,
                                Algebra, Operations, Resizer>,
      Order, StepperOrder, ErrorOrder, State, Value, Deriv, Time, Algebra, Operations, Resizer>
      stepper_base_type;
#else
  typedef explicit_stepper_base<...> stepper_base_type;
#endif
  typedef typename stepper_base_type::state_type state_type;
  typedef typename stepper_base_type::wrapped_state_type wrapped_state_type;
  typedef typename stepper_base_type::value_type value_type;
  typedef typename stepper_base_type::deriv_type deriv_type;
  typedef typename stepper_base_type::wrapped_deriv_type wrapped_deriv_type;
  typedef typename stepper_base_type::time_type time_type;
  typedef typename stepper_base_type::algebra_type algebra_type;
  typedef typename stepper_base_type::operations_type operations_type;
  typedef typename stepper_base_type::resizer_type resizer_type;
#ifndef DOXYGEN_SKIP
  typedef explicit_error_generic_rk<StageCount, Order, StepperOrder, ErrorOrder, State, Value, Deriv,
                                    Time, Algebra, Operations, Resizer>
      stepper_type;
#endif
  typedef detail::generic_rk_algorithm<StageCount, Value, Algebra, Operations> rk_algorithm_type;

  typedef typename rk_algorithm_type::coef_a_type coef_a_type;
  typedef typename rk_algorithm_type::coef_b_type coef_b_type;
  typedef typename rk_algorithm_type::coef_c_type coef_c_type;

  static const size_t stage_count = StageCount;

private:
public:
  // we use an explicit_generic_rk to do the normal rk step
  // and add a separate calculation of the error estimate afterwards
  explicit_error_generic_rk(const coef_a_type& a, const coef_b_type& b, const coef_b_type& b2,
                            const coef_c_type& c, const algebra_type& algebra = algebra_type())
    : stepper_base_type(algebra), m_rk_algorithm(a, b, c), m_b2(b2) {
  }

  template <class System, class StateIn, class DerivIn, class StateOut, class Err>
  void do_step_impl(System system, const StateIn& in, const DerivIn& dxdt, time_type t, StateOut& out,
                    time_type dt, Err& xerr) {
    // normal step
    do_step_impl(system, in, dxdt, t, out, dt);

    // additionally, perform the error calculation
    detail::template generic_rk_call_algebra<StageCount, algebra_type>()(
        stepper_base_type::m_algebra, xerr, dxdt, m_F,
        detail::generic_rk_scale_sum_err<StageCount, operations_type, value_type, time_type>(m_b2, dt));
  }

  template <class System, class StateIn, class DerivIn, class StateOut>
  void do_step_impl(System system, const StateIn& in, const DerivIn& dxdt, time_type t, StateOut& out,
                    time_type dt) {
    m_resizer.adjust_size(
        in, detail::bind(&stepper_type::template resize_impl<StateIn>, detail::ref(*this), detail::_1));

    // actual calculation done in generic_rk.hpp
    m_rk_algorithm.do_step(stepper_base_type::m_algebra, system, in, dxdt, t, out, dt, m_x_tmp.m_v, m_F);
  }

  template <class StateIn>
  void adjust_size(const StateIn& x) {
    resize_impl(x);
    stepper_base_type::adjust_size(x);
  }

private:
  template <class StateIn>
  bool resize_impl(const StateIn& x) {
    bool resized(false);
    resized |= adjust_size_by_resizeability(m_x_tmp, x, typename is_resizeable<state_type>::type());
    for (size_t i = 0; i < StageCount - 1; ++i) {
      resized |= adjust_size_by_resizeability(m_F[i], x, typename is_resizeable<deriv_type>::type());
    }
    return resized;
  }

  rk_algorithm_type m_rk_algorithm;
  coef_b_type m_b2;

  resizer_type m_resizer;

  wrapped_state_type m_x_tmp;
  wrapped_deriv_type m_F[StageCount - 1];
};

/********* DOXYGEN *********/

/**
 * \class explicit_error_generic_rk
 * \brief A generic implementation of explicit Runge-Kutta algorithms with error estimation. This class
 * is as a
 * base class for all explicit Runge-Kutta steppers with error estimation.
 *
 * This class implements the explicit Runge-Kutta algorithms with error estimation in a generic way.
 * The Butcher tableau is passed to the stepper which constructs the stepper scheme with the help of a
 * template-metaprogramming algorithm. ToDo : Add example!
 *
 * This class derives explicit_error_stepper_base which provides the stepper interface.
 *
 * \tparam StageCount The number of stages of the Runge-Kutta algorithm.
 * \tparam Order The order of a stepper if the stepper is used without error estimation.
 * \tparam StepperOrder The order of a step if the stepper is used with error estimation. Usually Order
 * and StepperOrder have
 * the same value.
 * \tparam ErrorOrder The order of the error step if the stepper is used with error estimation.
 * \tparam State The type representing the state of the ODE.
 * \tparam Value The floating point type which is used in the computations.
 * \tparam Time The type representing the independent variable - the time - of the ODE.
 * \tparam Algebra The algebra type.
 * \tparam Operations The operations type.
 * \tparam Resizer The resizer policy type.
 */

/**
 * \fn explicit_error_generic_rk::explicit_error_generic_rk( const coef_a_type &a , const coef_b_type &b
 * , const coef_b_type &b2 , const coef_c_type &c , const algebra_type &algebra )
 * \brief Constructs the explicit_error_generik_rk class with the given parameters a, b, b2 and c. See
 * examples section for details on the coefficients.
 *
 * \param a Triangular matrix of parameters b in the Butcher tableau.
 * \param b Last row of the butcher tableau.
 * \param b2 Parameters for lower-order evaluation to estimate the error.
 * \param c Parameters to calculate the time points in the Butcher tableau.
 * \param algebra A copy of algebra is made and stored inside explicit_stepper_base.
 */

/**
 * \fn explicit_error_generic_rk::do_step_impl( System system , const StateIn &in , const DerivIn &dxdt ,
 * time_type t , StateOut &out , time_type dt , Err &xerr )
 * \brief This method performs one step. The derivative `dxdt` of `in` at the time `t` is passed to the
 * method.
 * The result is updated out-of-place, hence the input is in `in` and the output in `out`. Futhermore, an
 * estimation of the error is stored in `xerr`. `do_step_impl` is used by explicit_error_stepper_base.
 *
 * \param system The system function to solve, hence the r.h.s. of the ODE. It must fulfill the
 *               Simple System concept.
 * \param in The state of the ODE which should be solved. in is not modified in this method
 * \param dxdt The derivative of x at t.
 * \param t The value of the time, at which the step should be performed.
 * \param out The result of the step is written in out.
 * \param dt The step size.
 * \param xerr The result of the error estimation is written in xerr.
 */

/**
 * \fn explicit_error_generic_rk::do_step_impl( System system , const StateIn &in , const DerivIn &dxdt ,
 * time_type t , StateOut &out , time_type dt )
 * \brief This method performs one step. The derivative `dxdt` of `in` at the time `t` is passed to the
 * method.
 * The result is updated out-of-place, hence the input is in `in` and the output in `out`.
 * Access to this step functionality is provided by explicit_stepper_base and
 * `do_step_impl` should not be called directly.
 *
 * \param system The system function to solve, hence the r.h.s. of the ODE. It must fulfill the
 *               Simple System concept.
 * \param in The state of the ODE which should be solved. in is not modified in this method
 * \param dxdt The derivative of x at t.
 * \param t The value of the time, at which the step should be performed.
 * \param out The result of the step is written in out.
 * \param dt The step size.
 */

/**
 * \fn explicit_error_generic_rk::adjust_size( const StateIn &x )
 * \brief Adjust the size of all temporaries in the stepper manually.
 * \param x A state from which the size of the temporaries to be resized is deduced.
 */
}
}
}

#endif  // BOOST_NUMERIC_ODEINT_STEPPER_EXPLICIT_ERROR_GENERIC_RK_HPP_INCLUDED
